Ignition UA-OPC Connection Issue

Hello to everyone, I want to request your support due to some issue we are currently experiencing with our Ignition License. We are not able to have connection with the Ignition OPC-UA Server Tags. The devices connection is OK, and if I check the quickclient OPC, the tags are displayed correctly. However when I export the Tags from the Quick Client to my ignition project, I got a NULL value from them, and the tag is highlighted in red, reflecting a bad quality. This error happened 2 days ago, but we are not sure when or why did it happen. Do you have any idea of what could cause this and how can we solve it?